The present invention relates to waveguide antennae, and more particularly to dual polarized waveguide slot array antennae.
Waveguide slot array antennae are well known in the art, and are typically employed for providing high power capability in applications, such as base station transmitting antenna arrays.
FIG. 7A illustrates a conventional vertically-polarized waveguide slot array 700 as known in the art. The array 700 includes a waveguide slot body 710 which is operable to support the propagation of a signal along a longitudinal axis 712 (z-axis) of the waveguide slot body 710. Transverse to the longitudinal axis 712, the waveguide slot body 710 defines a waveguide aperture having a major dimension 713 (along the x-axis) and a minor dimension 714 (along the y-axis). The major dimension 713 defines the lowest frequency of operation for the array 700, and is typically 0.5λ in its dimension. The waveguide slot body 710 further includes edge slots 722 and 724, each angled a in respective positive and negative angular orientations relative to the axis of the minor dimension 714. An end cap 730 is located at the top of the array 700.
FIG. 7B illustrates typical radiation patterns 750 for the vertically-polarized waveguide slot array 700 of FIG. 7A. The patterns 750 include an azimuth radiation pattern 752 and an elevation pattern 754. The azimuth radiation pattern 752 exhibits 8 dB variation, as shown.
FIG. 8A illustrates a conventional horizontally-polarized waveguide slot array 800 with horizontal polarization as known in the art. The array 800 includes a waveguide slot body 810 which is operable to support the propagation of a signal along a longitudinal axis 812 (z-axis) of the waveguide slot body 810. Transverse to the longitudinal axis 812, the waveguide slot body 810 defines a waveguide aperture having a major dimension 813 (along the x-axis) and a minor dimension 814 (along the y-axis). The major dimension 813 defines the lowest frequency of operation for the array 800, and is typically 0.5λ in its dimension. The waveguide slot body 810 further includes longitudinal slots 820, each slot offset a predefined distance from a center line defining the major axis 812 of the waveguide body 810, adjacent slots offset in opposing directions from the center line. An end cap 830 is located at the top of the array 800.
FIG. 8B illustrates typical radiation patterns 850 for the horizontally-polarized waveguide slot array 800 of FIG. 8A. The patterns 850 include an azimuth radiation pattern 852 and an elevation pattern 854. The azimuth radiation pattern 852 exhibits 4 dB variation, as shown.
As can be observed, the azimuth radiation patterns for each of the conventional vertically and horizontally-polarized waveguide slot arrays vary significantly over the coverage area, meaning that signal levels over these coverage areas vary greatly as a function of the user's position. As a result, a high power transmitter or a high gain antenna is needed to ensure that the minimum signal level is provided to all users, independent of their location. Accordingly, although slot arrays are suitable for high power transmission and reception applications, they cannot be fully deployed in applications where more uniform coverage is needed.
What is accordingly needed is a waveguide slot array which can provide a more uniform radiation pattern.